Article

Amphibians, Reptiles, and Birds at Barrett’s Farm

Left: A 2-story, brown wooden house with trees in the backgr a steep roof, a chimney, two front doors, and multiple windows, on a plot of open land with some leafless trees. Right: Green farmland with a wooden fence in the foreground and bluesky. — The restored Colonel James Barrett House (left) and farmland (right) at Barrett’s Farm, Minute Man National Historical Park.
Photos: NPS (left) and NPS / Teá Montagna (right)

On the eve of April 19, 1775, about 700 British soldiers marched from Boston to Concord, Massachusetts, to seize colonial military supplies—an action that sparked the first battle of the American Revolution. Colonists from dozens of towns responded, marching throughout the night to intercept the British troops. What frogs, birds, and insects could be heard during this significant night? Are these species still present today? Did the sounds of wetland animals, such as spring peepers, serve as harbingers of difficult terrain and danger? The National Park Service (NPS) and its partners recently undertook a project to study the amphibians, reptiles, and birds found at Barrett's Farm—the destination of British troops 250 years ago.

Barrett’s Farm—Then and Now

The land at Barrett’s Farm has been farmed continuously for centuries, including the time leading up to the American Revolution, when the property was owned by Colonel James Barrett. Colonel Barrett was the commander of the 3^rd Middlesex Militia Regiment in 1775, and his farm was used to store arms and supplies for the militia (some of whom were known as Minute Men). On April 19, 1775, British soldiers searched Colonel Barrett’s house for stockpiles of militia arms and ammunition. Although the British did not find any stockpiles at the house that day (because they had been moved), the colonel and his family played significant roles in the first battle of the Revolutionary War.

A calm, shallow-appearing river with fairly dense, mostly green trees and shrubs along the bank. — A view at the confluence of Spencer Brook and the Assabet River, along the boundary of Minute Man NHP.
Photo: NPS / Teá Montagna

The Barrett’s Farm Unit (referred to as Barrett’s Farm in this article), became part of Minute Man National Historical Park (NHP) in 2012. Barrett’s Farm, 62 acres in size, is located in Concord, Massachusetts, while other parts of Minute Man NHP are in Lexington and Lincoln. The NPS owns the area that includes the Barrett House, while the Town of Concord owns much of the 62 acres, including an area managed as an organic farm. Park visitors use Barrett’s Farm for hiking, dog walking, fishing, and observing nature, as well as historical contemplation. The site is a well-known location for bird watching, especially during spring and fall migrations. Habitats at Barrett’s Farm include woodlands, wetlands, farmland, edge habitat, Spencer Brook, and the Assabet River, which is part of the National Wild and Scenic River System. Previous natural resource inventories at Minute Man NHP did not include the more recently acquired Barrett’s Farm, so the NPS and its partners, biologists with the University of Massachusetts, Boston, set out to determine what’s there.

What Types of Wildlife are at Barrett’s Farm Today?

To answer this question, University of Massachusetts, Boston, researchers focused their assessment on amphibians, reptiles, and birds. Biologists also looked at the plant communities and wetlands on site. They carried out field surveys and analyzed new and historical data, including “citizen science” data (data collected by community members).

Amphibians and Reptiles

Illustration of a spotted salamander. A dark amphibian with yellow spots. — Spotted salamander

How did we survey for amphibians and reptiles?
Biologists surveyed for amphibians and reptiles at Barrett’s Farm in three ways: with coverboards, through incidental encounters, and with environmental DNA.

(On left) a wooden coverboard lying on the ground in a wet, mucky location. (On right) a corrugated metal coverboard lying on the ground in a location that appears dry and with dead plants. — Photos of wooden (left) and metal (right) coverboards, which measured 2 ft wide by 4 ft long.
Photos: NPS / Nina McDonnell

Coverboards are wooden boards or metal sheets that are placed on the ground to create desirable conditions underneath for amphibians or reptiles seeking refuge. Wooden boards generally create cool and moist conditions that attract amphibians, and metal sheets generally create warm and dry conditions that attract reptiles. At Barrett’s Farm, biologists placed coverboards throughout the site in edge and woodland habitats, adjacent to seasonal pools and wetlands, and along river and stream beds. Boards of the same material were placed at least 66 feet (20 meters) apart. A wooden board and a metal sheet were usually placed near one another to attract both amphibians and reptiles. Coverboards were placed in the environment from March 2023 to September 2023 and checked every week or every other week (as weather/conditions allowed).

Biologists also recorded observations of amphibians and reptiles (and other animals) while walking the site during coverboard surveys. These incidental encounters provided valuable supplemental data because not all amphibians and reptiles tend to seek cover under coverboards.

Finally, biologists sampled for amphibians and reptiles through the use of environmental DNA, or eDNA. This method is based on the premise that organisms inhabiting an environment will shed genetic material through waste, dead cells, and other products. By collecting this material in water or soil samples, researchers can extract and amplify the DNA to identify individual species. To sample eDNA, biologists collected water samples in 2023 from eight locations at Barrett’s Farm in April, July, and October. See the main report (Montagna et al. 2024) for more details on eDNA methods.

What types of amphibians and reptiles did we find?
During the amphibian and reptile coverboard surveys and incidental observations during the surveys, biologists documented ten species at Barrett’s Farm that are commonly found in Massachusetts—4 frogs, 1 toad, 2 salamanders, 1 snake, and 2 turtles. Only three of the species were observed under coverboards during the surveys, while nine of the species were observed incidentally (mostly via a visual, but some via a call). Results from the eDNA sampling indicated the presence of four of the species found by the coverboard/incidental surveys and the wood frog (Lithobates sylvaticus, not documented otherwise during the study). All 11 species (see Table 1) have previously been found in other parts of Minute Man NHP.

Table 1. Amphibian and reptile species documented at Barrett’s Farm during our study: who and how.

Species Common Name	Species Latin Name	How was it observed?
Northern Leopard Frog	Lithobates pipiens	Incidental encounter, eDNA
Green Frog	Lithobates clamitans	Coverboard, Incidental encounter, eDNA
Bullfrog	Lithobates catesbeianus	Incidental encounter
Wood Frog	Lithobates sylvaticus	eDNA
Gray Treefrog	Dryophytes versicolor	Incidental encounter, eDNA
American Toad	Anaxyrus americanus	Incidental encounter, eDNA
Spotted Salamander	Ambystoma maculatum	Incidental encounter
Redback Salamander	Plethodon cinereus	Coverboard
Eastern Garter Snake	Thamnophis sirtalis	Coverboard, Incidental encounter
Painted Turtle	Chrysemys picta	Incidental encounter
Snapping turtle	Chelydra serpentina	Incidental encounter

Two of the species, the northern leopard frog and green frog, were documented in relatively large numbers (52 and 31 individuals, respectively) through incidental encounters. Biologists observed northern leopard frogs in many places around the farm, with the greatest concentration along the Assabet River and Spencer Brook. Eastern garter snakes were documented 15 times under coverboards and eight times in incidental encounters.

Top left—A frog (light brown with yellow brown spots) in grass.
Top right—A small brown toad with bumpy skin held in a person’s hand.
Bottom right—A brown and yellow snake partially coiled.
Bottom left—A gray salamander with yellow spots. — Photos of a few of the amphibians and reptiles observed during the 2023 study. Clockwise from top left: northern leopard frog, American toad, eastern garter snake, and spotted salamander.
Photos: NPS / Teá Montagna for the first three photos, and NPS / Robert Stevenson and Nina McDonnell for the last photo (spotted salamander)

Regarding our opening questions about which amphibians might have been heard on the eve of the first battle of the American Revolution, note that wood frogs and spring peepers (Pseudacris crucifer) are typically the first frogs to vocalize in the spring in Massachusetts. The wood frog was detected in our study through eDNA. Although biologists could hear spring peepers across the river from the park, none were heard in the park during our study. Another early vocalizer is the American toad, which was found during our study through both incidental encounters and eDNA.

Birds

How did we determine which birds are present?
Because annual, volunteer bird monitoring is not conducted at Barrett’s Farm, as it is in other parts of Minute Man NHP, University of Massachusetts, Boston, biologists used data from eBird to determine which bird species occur at Barrett’s Farm. eBird is a citizen science application that tracks individual bird observations from around the world. Data were available for Barrett’s Farm (the eBird location is called “Barrett’s Mill Farmland”) for 2005 to 2023. The data included 455 samples (a sample being an individual checklist of observations submitted for a particular date). Eight of the samples were from mid/late May through June—the time period typically used for breeding bird surveys in Massachusetts.

Illustration of an oriole, a small black and orange songbird. — Baltimore oriole

In addition to looking at the bird species reported in eBird for the Barrett’s Farm location, biologists assessed the conditions of forest and grassland bird communities using the eBird data and based on methods used by the NPS Northeast Temperate Inventory and Monitoring Network. Based on a numerical scoring system, the integrity of a community was rated in one of three categories—good, caution, or significant concern. For details on the methods, see our full report’s section on birds (Montagna et al. 2024).

How many and which species have been reported?
A total of 163 bird species have been reported at Barrett’s Farm from 2005 to 2023 via eBird. These species include Baltimore oriole (Icterus galbula), hermit thrush (Catharus guttatus), and white-crowned sparrow (Zonotrichia leucophrys), shown below, as well as northern cardinal (Cardinalis cardinalis), downy woodpecker (Dryobates pubescens), Canada goose (Branta canadensis), mallard (Anas platyrhynchos), and wild turkey (Meleagris gallopavo). This latter group of birds (starting with northern cardinal) was also identified through our eDNA sampling. Also, although we don’t know which bird species were calling on the eve of the first battle of the American Revolution, we do know that owl species have been reported at present-day Barrett’s Farm. The eBird observations included reports of barred owl (Strix varia) and great horned owl (Bubo virginianus). A barred owl’s hoot sounds like “Who cooks for you? Who cooks for you-all?” A great-horned owl’s hoot sounds something like “hoo-hHOO-hoo-hoo”, but they make lots of other sounds too!

For a complete list of the 163 species reported from 2005 to 2023 at Barrett’s Farm, see the appendix of our full report (Montagna et al. 2024). For a checklist of birds for the entire park, see the Friends of Minute Man National Park website.

Left—Close-up photo of a bird’s head; brown head with a pale throat with brown spots. Right—A small bird, with orange beak and legs, a light throat and belly, and black and white stripes on head. — Two bird species known to occur at Barrett’s Farm—hermit thrush (left) and white-crowned sparrow (right).
Photos: ©Robert Shantz

Using the eBird data and the formal assessment method mentioned in the previous section, biologists found an overall “caution” rating for breeding forest birds and an overall “significant concern” rating for grassland birds. It should be noted, however, that these outcomes are not surprising given the large proportion of actively farmed acreage and edge habitat at Barrett’s Farm. Also, a relatively small proportion of the samples (8 out of 455) were from the time period typically used for breeding bird surveys.

If you’d like to hear an audio recording of a hermit thrush or a white-crowned sparrow, click here.

Are There Gaps in our Information?

There are some remaining gaps in our information. While the current study presented findings of the coverboard sampling, eDNA sampling, incidental encounters, and eBird analyses, the study lacked enough information to fully assess the composition, condition, and seasonality of amphibians, reptiles, and birds. For example, future work could examine the importance of Barrett’s Farm for migrating birds and the importance of the river corridor for birds and other wildlife. Also, park managers would benefit from having more information on the site’s wetlands, including their biodiversity, water quality, and other key characteristics. Additionally, information is especially lacking on some animal groups at Barrett’s Farm, such as mammals, fish, and arthropods (including insects).

Illustration of a painted turtle. A turtle with natural red and yellow markings. — Painted turtle

The Importance of this Study

This study is important because it provides vital information on Barrett’s Farm to park staff and managers. It’s important to know what types of animals, plants, and habitats are present, and in what condition, in order to know how best to protect and manage for them. For example:

The information gathered will inform management decisions as the park and partners increase public visitation at Barrett’s Farm.
The study found a high number of invasive plant species. With this information, managers can prioritize areas for invasive plant removal.
The information gathered will help the NPS create natural resource-themed interpretive signs on the NPS-owned land at Barrett’s Farm along the historic Battle Road.

Near the close of this project, managers and partners at Minute Man NHP held a week-long BioBlitz. During the BioBlitz, focused on Barrett’s Farm, community scientists, park visitors, and professional specialists worked together to identify as many plant and animal species as possible. The event revealed new species residing in and migrating through the park, as well as information on the changing phenology due to climate change. Results of the mid-May BioBlitz will take some time to process, but see photos and links below for some information. BioBlitzes are a way for everyone to participate in collecting vital information for our parks!

Left: Two people are kneeling and taking a photo of a very small snake on the ground. Right: One person handles a very small turtle as a second person keeps their hands below; a third person stands next to them, and no faces are visible. — Participants at the Minute Man NHP May 2024 BioBlitz. Participants on the left have found a ring-necked snake, and those on the right have found a recently hatched painted turtle.
Photos: NPS / Minute Man NHP

If You Want To Learn More…

Minute Man NHP website has photos and descriptions of some of the reptiles and amphibians, as well as birds and mammals, that occur in the park.
Information on the May 2024 BioBlitz at Minute Man NHP can be found at this iNaturalist location: Battle Road BioBlitz 2024 · iNaturalist.
The NPS maintains information on older BioBlitzes nationwide at this location: The NPS/National Geographic Society BioBlitzes - Biodiversity (U.S. National Park Service).
A 24-hour, July 2019 BioBlitz at nearby Walden Woods found more than 2,200 animal and plant species: Great Walden BioBlitz | The Walden Woods Project. This BioBlitz included the park and other areas outside of Walden Woods.
This website of the non-profit Mass Audubon provides information on amphibians (including the loud ones!) during the spring: The Biggest Night(s) of Spring (massaudubon.org).
To hear the fascinating calls, songs, and sounds of numerous bird species, amphibians, and other animals, visit Cornell University’s Macaulay Library.

Information in this article is based primarily on: Montagna T and Others. 2024. Natural resource assessment of the Barrett’s Farm Unit: Minute Man National Historical Park. Science Report. NPS/SR—2024/216. National Park Service. Fort Collins, Colorado.